Various constructions of interlocking sheet metal panels have been proposed for assembling into a roof having upstanding joints or seams between the panels. This type of roof is sometimes called a "standing seam" roof and is frequently laid over insulation and supported upon the roof substructure. The insulation may be in the form of strips or panels supported on the roof purlins.
Many of the prior interlocking panels have had inter-engaging flanges requiring rolling or other metal-forming operations to seal the joints, or the application of special interlocking strips after the panels have been laid on the roof in order to form weather-tight seals. The use of such expedients in installing a roof is time-consuming and expensive, and the results are often unsatisfactory.
U.S. Pat. No. 4,269,012 shows one form of sheet metal panels having upstanding interlocking male and female edges in which the interlocking is accomplished by positioning one panel with its web flat on the roof substructure, then lifting the next panel so that its web is nearly vertical and its female edge flange is hooked over the male edge flange of the first panel, and then rotating the second panel downwardly until its web lays flat on the roof substructure. The male edge flange of each panel is secured ENC. to a roof purlin by clips hooked into the top of the flange and extending downwardly through insulation strips for securement to the purlin.
U.S. Pat. No. 4,106,250 shows another form of sheet metal panels having interlocking edges in which one panel is positioned flat on the roof and secured directly to a roof purlin, and the female edge flange of the next panel is lifted over the male edge flange of the first panel and forced downwardly into interlocking engagement therewith.
Both of these patented constructions require lifting of all or one side of one panel during the interlocking operation, and because these panels are long, unwieldy and easily distortable, the operation becomes difficult and tedious. Moreover, if insulation is required between the roofing panels and the roof substructure, it may be separately installed before the roof panels are laid, or if the insulation is pre-attached it results in a heavier and more unwieldy panel to be lifted and manipulated during the interlocking operation.